The present invention generally relates to blade or knife sharpening devices. More specifically, the present invention relates to a blade sharpening device that can sharpen blades to provide a consistent and uniform angle along the edge of the blade.
In the industry, it is well known to sharpen blades using a blade sharpening device. Several industries and persons require a sharp blade in their business operations: knife sharpeners, chefs, knife retailers, military, knife manufacturers, restaurants, knife distributors, hardware retailers, cutlery retailers, hardware wholesalers, cutlery wholesalers, agriculture, knife collecting clubs, landscapers, farmers/harvesters, hunters, lawn mower retailers, fishermen, outdoor products distributors, woodworkers, handymen, law enforcement, police, campers, tool retailers, house painters, automotive painting, carpet Installers, upholstery, linoleum installers, winery (pruning), and gardeners.
In order to sharpen a blade, the following issues must be addressed: the angle of the grinding medium to the edge of the blade, the path that the grinding medium follows, consistency of the above two factors throughout the sharpening course, the shape of the grinding medium, and the temperature of the blade during sharpening.
One method of blade sharpening involves using a grinding medium and the skill of the user. The main purpose of the grinding medium is to use something harder than the metal of the blade and grind the blade against it, manually, with little assistance to the user in controlling the angle of the blade. This grinding medium typically consists of grinding stones made of diamond, silicon carbide, aluminum oxide, soft and hard Arkansas, ceramic, and Japanese water stones.
The drawback to using a grinding medium without further assistance is the skill required by the user is an art that is difficult to obtain for ordinary users of the grinding medium. It can produce excellent results provided that the user has the proper know-how and proper coordination. Attempting to sharpen a blade without the proper technique can result in permanent damage of the blade. Sharpening by hand is not for the amateur and it is best when performed by professional knife sharpeners.
Another drawback to this method of sharpening is the time and effort involved in sharpening blades. The user must grind the blade against the stone several times in order to “raise a burr”, the sign that a side of the edge is sharpened. The same procedure must be done on the other side of the blade. Using stones of different grits multiplies the process by several times. Typically, at least two grits of stone and a honing/polishing must be used to properly sharpen a dull blade. This process requires at least 10-20 minutes per blade.
Other methods of blade sharpening address how to maintain a proper angle of the blade against the grinding medium. This category includes several types of devices such as guides, rod guides, crock sticks, slot gadgets, slide sharp, Skarb® system, and warthog system. Each of these devices will be described in further detail below.
Guides, such as the Buck Hone Master® and Razor® edge, assist the user in maintaining the proper angle of the blade to the grinding medium. The drawbacks are that the guides do not make use of the entire stone, the guide degrades during the sharpening process, and the path of the blade is still directed by the user which requires sufficient skill. In addition, it has many of the drawbacks discussed in the grinding medium above.
Rod-guided systems, such as Lansky®, GATCO®, Edge Pro Apex®, and DMT® systems, assist the user to maintain the angle of the blade to the grinding medium. More specifically, it is optimal for use of smaller sized blades. However, it has similar drawbacks featured in the guides and the grinding medium above.
Crock sticks, such as the Spyderco® system, Lansky® system, and Warthog® system, are another type of rod-guided system. With this system, the rods are held in a “V” at a predetermined angle and the blade is brought down against them in a slicing motion. It is another manual sharpening system and the user can make deviations from the set angle by tilting the blade. The drawback to this system is the rods are in a predetermined angle that the user will find difficult to adjust. It also has all the drawbacks of the previously mentioned rod-guided systems.
Slot gadgets, such as the Meyerco Sharpen-It System® and the Normark® sharpener, assist the user to maintain the angle of the blade relative to the grinding medium. With the slot gadgets, the user draws the blade through a slot a few times and this motion sharpens the blade. The drawback of these gadgets is that sometimes they damage the blade. When the slot gadget utilizes wheels, the blade changes shape over time. In addition, the overall quality of the sharpened blade is low.
The Skarb® system is a guide holding the blade in place while this system pivots on a vertical rod. It is a variation on the rod guided systems with low quality results since the angle is not kept the same throughout the blade (from 17 up to 30 degrees to the tip). Also, the Slide® sharp from CRKT® is another variation of the rod guided system having similar problems as the Skarb® (holding the angle throughout the blade).
Another method of sharpening blades involves the usage of power sharpeners. As in manual sharpening, power sharpening can be assisted or unassisted. Unassisted power sharpening involves, for example, two electric sharpeners—a belt sander and a bench grinder. With these electric sharpeners, the user passes the blade against the stone or the belt a few times to sharpen it. Sharpening blades with these two machines requires experience and skill. The belt sander or the stones are aggressive grinding mediums that can damage a blade in an unskilled user.
Assisted power sharpening is popular among both amateurs and professionals alike. The grinding medium is still a stone or a sand paper but the machines are outfitted with several guides or jigs to maintain a constant angle of the blade and guide the user for the proper sharpening. Two examples of assisted power sharpening are the Makita® and the Delta® with guides that help the user to adjust and keep the desired angle of the blade to the grinding medium.
Another two examples of assisted power sharpening are the Edge Craft's Chef® and the Fire Stone® from McGowan®. In this case, both machines use diamond hones for sharpening but the difference from the Makita® and the Delta® is that they have a guide that holds the blade in place so that the user does not wobble the blade during sharpening. They both have predetermined angles and three sets of wheels, two for sharpening and one for polishing/honing. The user makes a few passes from one slot to the other up to the polishing stage. These machines sometimes fail to produces a sharp edge on the blade and can scratch the sides of the blade.
On the professional grade, there are several types of sharpening systems. The Friedrich Dick® model, the True Hone® model, the Hook-Eye® belt grinder, and the Chef's Choice® professional are a few examples of some professional grade blade sharpening systems. Not all of them consistently create a razor edge on a blade. The machines are manufactured mainly for the purposes of a professional sharpener. Consequently, these devices still require some a skilled user for operation.
Finally, the Tormek® system uses a wet wheel and several guides and jigs for sharpening knives. It has a fully adjustable angle maker that sets the desired angle. It can grind out nicks or reshape broken tips without overheating the blade. It is an expensive tool designed for professional use. The jigs are sold separately, making it even more expensive.
In the prior art, the user's skill and “feeling” of the sharpening is paramount. The “art” part of the sharpening is still present in all of these prior art blade sharpening devices. The present invention solves the above problems in the prior art which results in a consistent, accurate and controlled process for sharpening with minimal user skill required. More importantly, the present invention directs a sharpening path of along a contour of the blade against an abrasive surface, with minimal user input. The present invention brings professional grade sharpening of the blade to the unskilled user with consist and uniform sharpening of the edge.